Several types of phospholipases are known which differ in their specificity according to the position of the bond attacked in the phospholipid molecule. Phospholipase A1 (PLA1) removes the 1-position fatty acid to produce free fatty acid and 1-lyso-2-acylphospholipid. Phospholipase A2 (PLA2) removes the 2-position fatty acid to produce free fatty acid and 1-acyl-2-lysophospholipid. The term phospholipase B (PLB) is used for phospholipases having both A1 and A2 activity. Phospholipase C (PLC) removes the phosphate moiety to produce 1,2 diacylglycerol and phosphate ester. Phospholipase D (PLD) produces 1,2-diacylglycerophosphate and base group.
Polypeptides having phospholipase activity may be applied in an industrial process, e.g., for refining of vegetable oils. Before consumption vegetable oils are degummed to provide refined storage stable vegetable oils of neutral taste and light color. The degumming process comprises removing the phospholipid components (the gum) from the triglyceride rich oil fraction.
Traditionally, the degumming process has been based on either water extraction, acidic or caustic treatment followed by a separation process. Due to the emulsifying properties of the phospholipid components, the degumming procedure has resulted in a loss of oil i.e. of triglycerides.
Enzymatic degumming reduces the oils loss due to an efficient hydrolysis of the phospholipids which decrease the emulsifying properties. However, present phospholipase A solutions are impaired by a need for a laborious pH adjustment procedure, and a generation of free fatty acids, while the only present commercially available phospholipase C (Purifine of Verenium, see Dijkstra, 101st AOCS Annual Meeting 10. May 2010), is dependent upon the species of the phospholipids in the oil, as it cannot hydrolyze the phosphatides phosphatidic acid and phosphatidyl inositol. Thus phosphatidic acid and phosphatidyl inositol will remain in the oil after the enzymatic degumming and the phospholipase C-treated oil must be further treated with caustic to remove the residual gums.
There is a need for further enzymes having phospholipase activity and suitable for application in enzymatic degumming of edible oils.